The subject matter described and/or illustrated herein relates generally to electrical terminals that terminate wires.
Electrical terminals are often used to terminate the ends of wires. Such electrical terminals typically include an electrical contact and a crimp barrel. The crimp barrel includes an opening that receives an end of the wire therein. The crimp barrel is crimped around the end of the wire to establish an electrical connection between the one or more conductors of the wire and the terminal as well as to mechanically hold the electrical terminal on the wire end. When crimped over the wire end, the crimp barrel establishes an electrical connection between the conductor(s) of the wire and the electrical contact.
Conductors of wires are often fabricated from copper. However, as the cost of copper has risen, aluminum has been considered as an alternative conductor material. However, aluminum is not without disadvantages. For example, one disadvantage of using aluminum as a conductor material is an oxide layer that may build on the exterior surface of the conductor. Such an oxide layer has relatively poor electrical conductivity. Accordingly, the oxide layer must be penetrated to the base material to establish a reliable electrical connection between the conductor and the electrical terminal.
Another disadvantage of aluminum is electrochemical corrosion. Many electrical terminals are used within environments that may expose the terminal and the wire crimped thereto to moisture. For example, electrical terminals are often used within automobiles and other vehicles that operate in salt-aqueous environments. Exposure of a conductor to moisture may cause the conductor to corrode. For example, moisture that infiltrates a crimp interface between a conductor and a crimp barrel may cause the conductor to experience electrochemical corrosion, and thereby begin to dissolve. Moreover, the end of many conductors is exposed at an end of the crimp barrel of the electrical terminal, for example through an opening within the end of the crimp barrel and/or because the end of the conductor extends past the end of the crimp barrel. Such exposed ends of conductors may experience corrosion from exposure to moisture within the operating environment of the electrical terminal. Corrosion is thus an issue when using aluminum as a conductor material. Moreover, the electrical terminal is optionally fabricated from copper based alloyed materials. In the electrochemical series copper and aluminum have a large difference in electrochemical potential, which is an indication for high corrosion speed. Corrosion may therefore be especially problematic when terminating aluminum conductors to copper-based electrical terminals.
A known attempt at prohibiting electrochemical corrosion includes preventing or reducing the exposure of a conductor to moisture. For example, attempts have been made to seal the ends of crimp barrels using silicone gaskets. However, because aluminum has a reduced amount of electrical conductivity relative to copper, aluminum conductors need to have a larger cross-sectional area than copper conductors for a given electrical current carrying capacity. When a copper conductor is replaced with an aluminum conductor, the space occupied by the silicone gasket may prevent the larger aluminum conductor from being used with the existing electrical terminal. A larger crimp barrel and silicone gasket would therefore need to be manufactured to accommodate the larger aluminum conductor, which may increase the cost of an assembly of the electrical terminal and wire.
Another attempt at prohibiting electrochemical corrosion includes decreasing the electrochemical potential between the conductor and the crimp barrel. Decreasing the electrochemical potential is accomplished by fabricating the crimp barrel or surfaces thereof from material which is closer to or substantially the same as the conductor. For aluminum conductors, possible materials of the crimp barrel include nickel plating, aluminum plating, and/or using an aluminum base material for the crimp barrel. However, such techniques are not without disadvantages. For example, nickel plating may require the use of galvanic plating, which may be relatively expensive. Additionally, the relatively hard nickel surface layer may be harmful to the tool used to crimp the crimp barrel around the wire. Moreover, there is a probability that the nickel surface layer will crack during crimping, which would create possible corrosion paths. Aluminum plating is not currently possible with usual plating process and may therefore require the implementation of new plating technology, such as physical vapor deposition (PVD), which may be expensive. Moreover, even with new plating technology such as PVD there will still be exposed edges of the plating layer, which will transfer the corrosion issue to a different place on the electrical terminal.
Fabricating the base material of the crimp barrel out of aluminum material may also be disadvantageous. Some electrical terminals include electrical contacts that are spring beams. However, aluminum has relatively poor spring characteristic properties, so there is no possibility to form a spring beam out of aluminum. Accordingly, fabricating the crimp barrel out of aluminum material would be restricted to use on electrical terminals that do not include a spring beam or it would be necessary to use different materials as the base materials of the crimp barrel and the electrical contacts, which may be expensive, time-consuming, and/or difficult to manufacture.